Aerosol apparatus and method of generating micronic size aerosol particles



4. 1969 J. E. JOHNSON ET AL 3,472,455

AEROSOL APPARATUS AND METHOD OF GENERATING MICRON-1C SIZE AEROSOL PARTICLES 2 Sheets-Sheet 1 Filed June 20, 1967 Na A mw w 5 M W mun V06 NJDFD 4 ERDW WME G EF W nl U E F CGK 4 2 4 N N s s S s x 5: m 6 M 2 u 1 r/ .w w|.|u 714 m u 3 W I, a A N 95 M m mm fi F Q w 2g w m A. P. N 3 w 2 Oct. 14, 1969 I J. E. JOHNSON ET AL 3,472,455 AEROSOL APPARATUS AND METHOD OF GENERATING MICRONIC SIZE AEROSOL PARTICLES Filed June 20. 196' 2 Sheets-Sheet 2 INVENTORS JAMES E. JOHNSON OL|FFORD G. PRlEST GERALD F LACKEY KENNETH D.SWONGEF United States Patent 3,472,455 AEROSOL APPARATUS AND METHOD OF GENERATING MICRONIC SIZE AEROSOL PARTICLES James E. Johnson, Clifford G. Priest, Gerald F. Lackey,

and Kenneth D. Swonger, Winston-Salem, N.C., assignors to Paramedical Research and Development Corporation, Winston-Salem, N.C., a corporation of North Carolina Filed June 20, 1967, Ser. No. 651,347 Int. Cl. B05b 1/24, 7/26; A61m 11/02 U.S. Cl. 239135 12 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an aerosol apparatus used for supplying conditioned aerosol mist for breathing for invalids such as those recovering from sickness or having respiratory ailments, and more particularly to an aerosol generator whereby an air jet breaks the tensioned surface strata of accumulated liquid into fine particles which are then thrust against a wedge-shaped battle to be subdivided into micronic sized particles.

BACKGROUND, BRIEF SUMMARY, AND OBJEC- TIVES OF THE INVENTION There are many circumstances under which it is desirable or essential that a mist of water and/or medication be supplied to invalids. Complicated and unwieldy apparatus has conventionally been used to supply the conditioned mist to the patient, and such equipment is, in many instances, (1) ambiguous, (2) noisy, and (3) inadequate. (1) it is ambiguous because of the variety of pieces of equipment necessary; namely, an air compressor, nebulizer and stand for same, high pressure hose assembly to connect the nebulizer to the compressor, and a tubing assembly for conveying the mist to the patient. Due to size, Weight, and the number of pieces necessary, conventional apparatus requires some means of conveyance to the patients room and occupies considerable space at the bedside. (2) Air compressors presently used are noisy because there are no facilities for sound absorption; they are not enclosed and merely operate in an exposed manner within the patients room. (3) Apparatus presently used is inadequate because the output or volume of aerosol mist delivered to the patient most often is insufiicient. Also present devices are limited in application since equipment presently for use at the bedside usually cannot be used with a mask or a tent.

The present invention has been devised to eliminate the objections set forth above and to depart from conventional particle breakdown devices that utilize a venturi approach to generate the aerosol mist. The generating capabilities of the device are such that it can be placed in a room near the patient without the accompanying enclosing tent, and in that location, will provide sufiicient aerosol mist for a wide range of surgical and medical requirements. There are means for permitting a variation in delivery of the generated mist which greatly enhance the use of the device. It has the flexibility necessary so that it can be used with a mask, tent, and as a bedside unit. Additionally, the present invention is a portable unit thus eliminating the complicated and cumbersome apparatus normally required in this application, and it can be easily carried by a nurse or attendant to the patients room or from one room to another within the hospital facility.

More specifically, the present invention is an aerosol apparatus made up of an air compressor, a liquid reservoir for holding water or medication to be used, and an aerosol generating device cooperating with the compres- 3,472,455 Patented Oct. 14, 1969 ice sor and reservoir for generating the required mist. The aerosol generating device includes a liquid accumulator bowl, an air jet entering that bowl beneath the surface of the collected liquid and a battle mounted within the bowl and above the air jet so that the surface film of the liquid is broken into fine particles by the compressed air introduced through the air jet and thrust against the wedgeshaped bafiie to further divide these particles into micronic size and thus produce a conditioned breathing aerosol mist for respiratory patients and the like. Venturi means is used only to bring the liquid within the accumulator bowl for subsequent breakdown by the air jet. Additionally, means are supplied for retaining the liquid and generated mist at a substantially even temperature.

With the foregoing in mind, it is a primary object of the present invention to provide a readily portable apparatus of the type described which incorporates an aerosol mist delivery unit that may be easily adjusted for bedside use or combined with a mask for concentrated delivery at a needed body location.

A further object of the present invetnion is to provide an improved apparatus and method for generating and controlling the aerosol mist particularly with respect to the separation of larger liquid particles and the mixing of subdivided particles with air being deilvered. This is accomplished by an aerosol generating device of the type described which is constructed to break the tensioned surface strata of water in a collecting device by an air blast and then thrust the broken particles of liquid against a wedge-shaped bafile to subdivide those particles into additional particles of micronic size.

These and other objects and advantages of the invention will become apparent by referring to the following detailed description in conjunction with the accompanying FIGURE DESCRIPTION FIG. 1 is a perspective view of the exterior of the present aerosol apparatus showing the tubing assembly which conveys the mist to the patient extending from that exterior and being supported thereon.

FIG. 2 is a side elevational sectional view taken along lines 22 of FIG. 1 showing the liquid reservoir and the aerosol generating device positioned thereabove, the liquid and generated mist being held at a substantially consistent temperature by a heating device extending into the liquid reservoir.

FIG. 3 is an end elevational sectional view taken along the lines 3-3 of FIG. 2 showing the air compressor and its relationship to the reservoir held within the housing.

FIG. 4 is a plan sectional view of the present invention taken along the line 4-4 of FIG. 2 showing the connections made between the compressor and aerosol generating device and the positioning of that device within the liquid reservoir.

FIG. 5 is an end elevational sectional view of the present invention taken along the lines 5-5 of FIG. 4 showing the tubing supporting telescoping stanchion within the housing and the retractable electric cord return device positioned adjacent to the compressor.

FIG. 6 is a side elevational, sectional and fragmentary view of the upper portion of the housing of the present invention showing the interchangeability of the flexible tubing assembly from a second mist emitting opening remote from the aerosol generating device to a first-mist emitting opening above that device.

FIG. 7 is a plan view of the aerosol generating device showing the accumulator bowl, the liquid deflector, the suspended bafiie and the air jet positioned therebeneath.

FIG. 8 is a side elevational sectional view of the aerosol device taken along the lines 88 of FIG. 7 particularly disclosing the air and liquid passages extending there through and the interconnection between one air'passage and the liquid passage to form a venturi which is used only as the means for inducing the flow of liquid into the accumulator bowl.

FIG. 9 is a cross-sectional enlarged view of the wedgeshaped baflle held by the accumulator bowl of the aerosol generating device.

FIG. is an end elevational sectional view of the aerosol generating device illustrated in FIGS. 7 and 8 particularly showing the positioning of the wedge-shaped baffle of FIG. 9 within the bowl directly above the air jet extending therein.

DETAILED DESCRIPTION Referring now to the figures and particularly to FIG. 1, there is shown an aerosol apparatus generally designated 10 which particularly comprises, as shown throughout FIGS. 2 through 5, an air compressor 12 suitably mounted Within a housing 14 upon cushioning blocks 16 appropriately wired for electrical operation to a toggle switch 18 by an electrical conductor 20 wound about a retractable reel 22, the conductor being affixed to an outlet plug 24 for convenient coupling with any conventional electrical outlet (not shown). The compressor is suitably insulated to eliminate noise normally associated with its operation by means of an insulating material 21 such as fiber glass aluminum-backed accoustical padding aflixed to the interior wall 23 of housing 14. Reel 22 is spring biased so that it will immediately retract the conductor 20 upon disengagement of plug 24 from an electrical outlet. Within housing 14 is positioned a reservoir 26 adapted to hold water or medication in liquid form 28 for the aerosol generating operation subsequently to be described. The liquid 28 is preferably maintained at a level generally as shown in FIG. 2 so as to provide a partially empty chamber thereabove for the accumulation of mist to be distributed in a manner to be described. An aerosol generating device generally designated 30 extends within reservoir 26 and is coupled to the reservoir-contained liquid 28 by means of a tubular member 32 extending to the bottom 34 of the container. Padding 36 surrounds the reservoir so as to maintain proper position of the reservoir.

The housing 14 has a first mist emitting opening 38 and a second mist emitting opening 40 in its upper surface to provide an outlet for mist generated by the device, opening 38 located directly above the aerosol generating device so as to allow a heavier mist concentrate to be delivered to the patient, and a second opening 40 positioned remote from the aerosol generating apparatus to allow a lesser mist concentrate to pass therefrom in the event such is needed in a particular application.

The housing 14 is relatively simple in construction and is provided with a number of ventilating slits 42 at strategiclocations to allow adequate cooling for the motordriven air compressor 12. Additionally, a hinged lid 44 latchably securable 46 allows easy access to the interior of the reservoir when a supplemental quantity of liquid or maintenance is needed. A handle 48 is provided so that the unit may be easily carried from location to location to location as its size is relatively small and its weight is such that a nurse or attendant may handle the entire apparatus without undue strain. A telescoping stanchion 50 can be retracted within housing 14 when the unit is not in use and serves to support a flexible mist conveying tube assembly 52 extending from either of openings 38 or 40 so that the volume of the generated mist may be changed according to the needs of the patient. A slotted opening 54 within one wall of the housing 14 allows visual inspection of the liquid level within reservoir 26 in order that a shortage of liquid may be quickly sensed by the attendant.

The air output of compressor 12 is directed through a pressure tubing 56 which in turn connects with the aerosol generating device 30 to provide a suitable compressed air supply for'the'ae'rosol mist generatingoperation. A "so'fin'd absorbing filter 53 is positioned within tubing 56 to increase the sound suppressing characteristics of the device as well as filter out impurities and particles of foreign matter that might clog. or damage the system. It has been found advantageous to provide a heating element 58 within the reservoir, and extending beneath theliquid level so that the generated aerosol mist may be maintained at near body temperature.

The aerosol generating device 30is comprised of a liquid accumulator bowl shown generally as 60 having a circular bottom portion 62 which is surrounded by a continuous inclined wall 64in a manner best shown in FIG. 8. An inlet port 66 opens into the bowl 60 through the inclined wall 64, and a deflector 68 is secured to the wall 64 and bottom 62 in the manner shown directly in front of inlet port 66 so that liquid entering the bowl through the inlet port will be deflected substantially equally in two directions to fiow about the bowl 64 (see arrows in FIG. 7) and maintain the liquid accumulatedwithin the bowl 60 at an even and consistent level. The bidirectional flow of entering liquid allows the apparatus to be positioned in a less critical manner in that the liquid level covering the bowl bottom 62'will remain reasonably consistent even though the aerosol generating device be uneven and not precisely level.

Tubing 32 connects directly to passageway 70 within the bowl housing 72 and leads to inlet port 66. Liquid flow through tubing 32, passage 70 and inlet port 66 into the accumulator bowl 60 is accomplished by a venturi eflect created when an additional air jet 74 is extended from the main air passage 76 which communicates directly with pressure tubing 56 adjoining the compressor. Air flow through passage 76 and into passage 70 will, by a pressure differential, draw the liquid through tubing 32 from the reservoir 26, and consistent flow rate is maintained by uniform air flow through the additional air jet 74.

The primary air jet 78 extends perpendicularly from airpassage 76 into the very center of the bowl bottom 62, and the extension 80' of this air jet is to a position slightly above bottom 62 of bowl 60. When liquid 28 is moved from reservoir 26 into the bowl 60 in the manner described above, the air flow hrough the additional air jet 74 is calibrated and regulated so that the consistent liquid level maintained in the bowl is very slightly above the extended end 80 of air jet 78 as this will directly affect the generation of aerosol particles. Thus the liquid level in the bowl bottom 62 is such that the surface of the contained liquid barely covers the extended end 80' of air jet 78. The properties inherent in the surface tension of a liquid, the level of which is just above the extended end 80 of jet 78, causing a breakup of the liquid into fine particles in a very satisfactory manner and allows further movement of these particles by the compressed air.

A baflie generally designated 82 extends across bowl 60 directly above air jet 78 and is secured to the bowl wall 64 on opposite sides of the bowl. Bafile 82 has its lower slightly pointed section directed over the air jet extension 80 so that it serves as a divider to further separate and miniaturize liquid particles 84 broken away from the bowl-contained liquid by compressed air introduced through the jet 78. A plurality of micronic sized particles 84 are formed when the air jet 78 thrusts the fine particle's resulting from the breakup of the liquid surface slightly above the extended end 80 of the air jet 78 against the wedge-shaped end 86 of baflie 82. Thus the use of air jet 78 allows a breakup of the liquid surface under tension into fine particles, and these particles can then be thrust against the lower edge 86 of baffie 82 with such force that they are then divided and subdivided into particles 84 of micronic size. From these micronic sized particles is formed an aerosol mist which can be supplied as a conditioned breathing mist for invalids such as those recovering from sickness or having respiratory ailments. The particle size resulting from use of the present invention ranges from .5 micron to 5 microns and is suitable for a multitude of inhalation operations in hospitals and the like.

Thus the present invention in the broadest sense is an apparatus which comprises an air compressor 12, a liquid reservoir 26 and an aerosol generating device 30 cooperating with the compressor and reservoir to provide an terosol mist suitable for inhalation applications. The aerosol generating device is made up of an accumulator bowl 60 and a venturi connection adapted to move the liquid from the reservoir to the bowl for subsequent treatment by an air jet 78 fed by the compressor which extends into the bottom 62 of the bowl. A deflector 68 in the bowl introduces a bidirectional flow of liquid from the reservoir to maintain the surface level and liquid height above the bowl bottom uniform. The air jet, which extends slightly into the bowl and above the bowl bottom, then breaks up the tensioned surface strata of the contained liquid and thrusts the formed particles against a baffle 82 positioned directly above the air jet so that the fine particles are then subdivided into micronic size particles to form a mist. The generated mist can be conveyed through suitable apparatus to an inhalation mask, tent or used as a bedside unit.

The second portion of the present invention in the broadest sense is a method of generating an aerosol mist which includes the steps of introducing a quantity of fluid over an air jet so that only the very thin tensioned surface strata of the liquid covers the jet, breaking the surface strata of the liquid into fine liquid particles, thrusting the broken particles against a uniquely shaped bafiile to subdivide these particles into an aerosol mist of micronic size and subsequently moving the generated mist to any desired application.

From the foregoing it will be apparent that there has been provided an improved form of apparatus and an improved method for medical use, particularly in connection with the generation and delivery of aerosol mist for breathing. This apparatus and method provides a convenient means for inhaling finely suspended water or medicinal particles without the necessity of an enclosing canopy. A large volume of mist may be generated and delivered to the region of the patients face or body area to supply an aerosol mist of medically approved particle size. The controls of the device, including the two strategically positioned openings 38 and 40, permit accurate adjustment of the volume of mist concentration, and the construction further permits ready removal of the components of the device for inspection and cleaning.

We claim:

1. An aerosol apparatus comprising: an air compressor; a liquid reservoir proximate said compressor; and liquid aerosol generating means communicating with said compressor and said reservoir, said aerosol generating means including a liquid accumulator bowl, venturi means adapted to displace liquid from said reservoir to said bowl, an air jet communicating with said air compressor and extending into said bowl, a deflector within said bowl to cause flow of liquid from said reservoir into said bowl to maintain said liquid depth uniform within said bowl, and a baflle mounted within said bowl and above said air jet, said air jet extending into said bowl to a position slightly below the surface of liquid accumulated therein so that compressed air introduced through said jet will cause the liquid surface thereabove to be blown into fine particles against said baflle for further division into micronic sized particles to form an aerosol mist.

2. An apparatus as claimed in claim 1, said deflector adapted to induce bidirectional flow of liquid from said reservoir into said bowl.

3. An apparatus as claimed in claim 1 further comprising a housing enclosing said aerosol generating means and said reservoir, said housing having a first mist-emitting opening above said air jet and a second mist-emitting opening remote from said bowl and air jet.

4. An apparatus as claimed in claim 3 further comprising a flexible mist conveying tubing selectively securable to said first and second mist-emitting openings to provide varying concentration of mist formed from micronic liquid particles at predetermined locations.

5. An apparatus as claimed in claim 4 further comprising heating means within said reservoir and housing to maintain the contained liquid and generated mist at near body temperature.

6. An apparatus as claimed in claim 5, said deflector adapted to induce bidirectional flow of liquid from said reservoir into said bowl.

7. An aerosol generating device for producing micronic sized liquid particles comprising: a liquid accumulator bowl adapted to retain a quantity of liquid; an air jet opening into said bowl; a fluid inlet port within said bowl; means for introducing liquid into said bowl; a deflector adjacent said port adapted to induce liquid accumulation in said bowl at a uniform depth; and a bafile secured to said bowl positioned to divide liquid particles blown from said bowl by said air jet into a mist of micronic sized particles.

8. An aerosol generating device as claimed in claim 7, said deflector positioned adjacent to said port and adapted to induce bi-directional liquid flow into said bowl from said port.

9. An aerosol generating device as claimed in claim 8, said accumulator bowl having a circular bottom portion and a continuous inclined wall and said inlet port extending into said bowl through said wall.

10. An aerosol generating device as claimed in claim 9, said deflector secured to said bowl bottom and wall in front of said inlet port so that liquid entering therethrough will be deflected substantially equally in two directions to flow about the bowl wall and maintain liquid accumulated within the bowl at a consistent level.

11. An aerosol generating device as claimed in claim 10, said baffle having a wedge-shaped cross-sectional configuration, extending across said bowl and above said air jet and being secured to said bowl wall.

12. An aerosol generating device as claimed in claim 11, said air jet extending above the bottom of said bowl to a position just below the liquid surface so that air introduced through said jet will cause the tensioned liquid surface to be blown into fine particles against said baflle.

References Cited UNITED STATES PATENTS 1,859,935 5/1932 Potts et al 26 1-121 X 2,906,463 9/1959 Curry 239-338 3,097,645 7/1963 Lester 128-194 FOREIGN PATENTS 1,483,403 6/ 1967 France.

M. HENSON WOOD, 1a., Primary Examiner BERNARD BELKIN, Assistant Examiner US. Cl. X.R. 

